Showing papers by "Huijun Ren published in 2018"

Photocatalytic properties of the g-C3N4/{010} facets BiVO4 interface Z-Scheme photocatalysts induced by BiVO4 surface heterojunction

Abstract: The g-C3N4/{010} facets BiVO4 interface Z-scheme photocatalysts is fabricated by ultrasonic dispersion method. The density functional theory (DFT) shows that the differences of the energy levels in the conduction bands and the valence bands between the {010} and {110} facets of BiVO4 is about 0.37 and 0.31 V (vs. NHE, pH = 7), respectively. Therefore, the co-exposed {010} and {110} facets of BiVO4 can form surface heterojunction, which promotes the {010} facets of BiVO4 with negative charge. The zeta potential indicates that layered g-C3N4 with positive charge. The Raman, FT-IR and XPS analysis demonstrates that the layered g-C3N4 is anchored on the {010} facets of BiVO4 through strong interface electrostatic interaction, which leads to form a built-in electric field at the contact interface. Under the built-in electric field driving, photogenerated electrons in the CB of {010} facets of BiVO4 rapidly recombines with the holes in the VB of g-C3N4 to form the interface Z-scheme heterostructure. That is, BiVO4 surface heterojunction ultimately induces the formation of interface Z-scheme heterostructure. The interface Z-scheme heterostructure not only facilitates the space separation of the photogenerated carriers, but also accumulates electrons in the more negative potentiated CB of g-C3N4 and holes in the more positive VB of {110} facets of BiVO4. Consequently, by means of the I-t, LSV and EIS measurements, the g-C3N4/{010} facets of BiVO4 interface Z-scheme photocatalysts presents extraordinary photoelectrochemical performance. More importantly, the degradation rate of g-C3N4/{010} facets of BiVO4 interface Z-scheme photocatalysts can reach the highest 88.3% within 30 min under visible light irradiation, and the mineralization ability (96.03%) is about 2.24 and 3.32 times as high as that of BiVO4 (42.83%) and g-C3N4 (28.89%), respectively.

Tunable structural transition and multiferroic properties of the composite thin films through the structural transition of magnetic layer

Abstract: The Bi 0.9 Er 0.1 Fe 0.96 Mn 0.02 Co 0.02 O 3 /Co 1-x Mn x Fe 2 O 4 (BEFMCO/CM x FO) thin films have been deposited by sol-gel method. Structural distortion is observed in the BEFMCO with the appearance of trigonal-R-3m: H in the CM x FO. The enhanced multiferroic properties, well electrically writable and ferroelectric switching properties are obtained in BEFMCO/CM x FO thin films. The investigation indicates that the structural transformation of the CM x FO influences the structure and multiferroic properties of BEFMCO and the interfacial effects between BEFMCO and CM x FO layers. This transformation and Mn-doping cause the change of carriers, which solves the problem that the magnetic layer exacerbates the ferroelectric properties. It promotes to form the weak local electric field, which causes the weak interface effect, and brings out the weak resistive switching in the BEFMCO/CM x FO thin films. Therefore, it is believed that the BEFMCO/CM x FO films can offer a potentially tunable structural transformation of composite films for practical applications.

Resistance switching behavior and ferroelectric properties of the Bi 0.89 Ho 0.08 Sr 0.03 Fe 0.97−x Mn 0.03 Zn x O 3 thin films

Abstract: Bi0.89Ho0.08Sr0.03Fe0.97−xMn0.03Zn x O3 (BHSFMZn x O) thin films were prepared by a chemical solution deposition method on the fluorine doped tin oxide (FTO) substrates. The effects of Sr, Ho, Mn and Zn co-doping on the crystal structure, defects, leakage current, resistance switching behavior and ferroelectric properties of the BiFeO3 films were investigated. The results show that Zn2+ doped BHSFMO films lead to the transformation of the preferred orientation from (110) to (100). The oxygen vacancies, $${(Zn{\prime _{Fe}} - V_{O}^{{ \cdot \cdot }})^ \cdot },$$ leakage current density and the Schottky barrier of BHSFMZn x O films were increased with the increase of Zn2+ doping. The BHSFMZn0.04O film shows the highest resistance switching ratio (18.6) at 200 kV/cm. The BHSFMZn0.01O film have larger remanent polarization and switching current (P r ~ 135 µC/cm2 and I S ~ 1.5 mA), and the relatively low coercive field and the polarization leakage current (E c ~ 350 kV/cm and I L ~ 0.14 mA). Therefore, the resistance switching behavior or ferroelectric properties can be obtained by controlling the doping amount of Zn2+.